A500 SCSI controller which connects to the side expansion slot of the A500. Hard drives can be mounted inside the unit. Depending on the version you have, RAM can be added in the form of 70ns 30pin SIMMs or SIPPs for up to 8MB of RAM. Configurations of 2x1MB, 2x2MB, 2x4MB, or 4MB+2MB are possible. There may have also been drivers available to use this with the Medusa ST